CN109511028B

CN109511028B - Multi-driver earplug

Info

Publication number: CN109511028B
Application number: CN201811342160.9A
Authority: CN
Inventors: Y·阿茨米; A·D·查万
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2013-01-22
Filing date: 2013-12-23
Publication date: 2021-07-06
Anticipated expiration: 2033-12-23
Also published as: CN104956685A; KR101781710B1; TWI558168B; TW201433174A; HK1213122A1; US9055366B2; CN109511028A; WO2014116388A1; US20140205131A1; CN104956685B; KR20150108907A

Abstract

The present disclosure relates to a multi-driver earplug. The first driver housing and the second driver housing are positioned inside the earbud cup. The first driver housing has a rear side, a front side, a top surface, a bottom surface, and a sound output tube extending from the front side. The second driver housing has a top side, a bottom side, a front face, a rear face, and a sound output opening formed in the front face of the second housing, substantially without a tube extending therefrom. The rear face of the second housing is disposed a) adjacent to the front side of the first housing, and b) behind the outlet of the sound output tube of the first housing. Other embodiments are described and claimed.

Description

Multi-driver earplug

The present application is a divisional application of the invention patent application having application number 201380070986.3,

application date

2013, 12 and 23, entitled "multi-driver earplug".

Technical Field

Embodiments of the present invention relate to an earphone, also referred to as an earbud, having a crossover network and a plurality of speaker drivers, which fits in the ear canal of a user. Other embodiments are also described.

Background

In-ear headphones or earplugs continue to be popular because they can deliver adequate sound quality while having a convenient, compact profile and being lightweight. Professional quality in-ear headphones often use balanced armature drivers that can be designed to faithfully reproduce low or high frequency sounds. However, balanced armature drivers typically do not operate consistently throughout the entire audible frequency range. To overcome this limitation, it has been proposed to use multiple balanced armature drivers within the in-ear headphone. In that case a crossover network is also provided to divide the frequency spectrum of the audio signal into two regions, a low frequency region and a high frequency region, and to reproduce the sound in each region using a separate driver. Professional quality earphones may also have ear tips or ear muffs, which may be custom molded or generic, allowing a snug fit to acoustically seal the user's ear canal, which enables higher quality low frequency or bass sounds to be heard in addition to lower audible background noise.

A typical sealed type earplug has a housing or cup that houses a driver. A silicone or rubber boot with sound passages formed therein fits over the front end of the driver to hold the driver in place and ensure that the driver output is sealed from the outside environment. A cover of rigid material (as opposed to the material of the protective cover) is then pushed over the protective cover to substantially complete the rigid earphone housing. A spout extends from the front of the cover and is aligned with a passage in the protective cover to receive sound generated by the driver. The spout is then fitted with a flexible ear tip. While such an arrangement has proven effective in presenting adequate sound performance while being sufficiently small and light enough for everyday consumer users with a variety of activities, providing good sound fidelity over most, if not all, of the typical consumer hearing range, generic (i.e., non-custom) in-ear headphones suitable for mass manufacture present a challenge, particularly in packaging multiple drivers within the compact confines of the earbud housing.

Disclosure of Invention

An embodiment of the present invention is an earplug having an earplug cup in which a first driver housing and a second driver housing are disposed. The first driver housing has a rear side, a front side, a top side, a bottom side, and a sound output tube extending outwardly from the front side. The second driver housing has a top side, a bottom side, a front face, a rear face, and a sound output opening formed in the front face, but is substantially free of sound output tubes. The rear face of the second housing is disposed a) adjacent to the front side of the first housing, and b) behind the outlet of the sound output tube of the first housing.

In one case, in the first housing, the top face has a larger area than the rear side or the front side. Also, in the second housing, the front face has a larger area than the top side or the bottom side. An example of such a housing is a parallelepiped shaped driver, wherein the diaphragm in each housing may be arranged substantially parallel to a face of the housing instead of a side of the housing. Each driver housing may contain a single balanced armature driver to produce its respective sound.

In another embodiment, the earbud cup includes a low driver housing, a mid driver housing, and a high driver housing. The three housings are arranged opposite each other, so that a more compact envelope is obtained which is capable of producing sound with good fidelity. In particular, the mid and low driver housings are stacked on top of each other, i.e. the top face of the low housing rests substantially flat against the bottom face of the mid housing, while the high housing is oriented such that its rear face is arranged adjacent to the front side of the low housing and behind the outlet of the sound output tube of the mid housing. The sound output opening is formed in the front face of the tall enclosure but is substantially free of sound output tubes.

In one case, the high driver housing houses a single balanced armature motor coupled to drive a diaphragm oriented substantially parallel to the front and back of the high housing, while the low and medium driver housings may have balanced armatures or dynamically moving coil motors or a mixture of both. Such an arrangement works particularly well when the top face of the low driver housing has a larger area than the rear or front side of the low driver housing and the bottom face of the medium driver housing has a larger area than the front or rear side thereof. In one embodiment, each of the low and medium housings is substantially parallelepiped (e.g., rectangular shape of matchbox) with two opposing faces each having a larger area than either side of the housing.

In one embodiment, the driver housing fits into a boot, which may have sufficient flexibility and resiliency to hold the driver housing as a single component. Two channels are formed in the boot that align with the two sound output ports of the driver housing, respectively. In embodiments where the ear bud has at least three driver housings, the high driver housing may be given its own channel in the boot, while the low and medium driver housings must share another channel. In another embodiment, the boot has a third channel dedicated to the low enclosure, wherein another sound output tube extends outwardly and upwardly from the left or right side of the low driver enclosure and then connects with the dedicated channel in the boot. In that case, each of the three driver housings uses its own or corresponding passage through the protective cover.

To complete the earplug housing, a cover is provided having an opening that is aligned with and large enough to surround the outlet of the channel in the protective cover. The cover may be made of a material that is more rigid than the protective cover, e.g., similar to the material from which the housing or cup is made. The protective cover may fit into the front face of the lid such that the lid completely surrounds the protective cover; the lid can then be snap-fit or otherwise attached to the front of the cup. The spout can extend forward from the lid where it is aligned with the lid opening. The spout may provide an uninterrupted space in communication with the outlet ports of the first and second channels at the cover opening. A flexible ear tip may be fitted to the spout to provide a snug and acoustically sealed in-ear headphone experience for the user. In such embodiments, the nozzle may have an equivalent radius to length ratio in the range of 1/4 to 1/7 plus a constant. This particular range can work effectively with a relatively compact arrangement of three drive enclosures with dual or triple channel versions of the protective cover.

In yet another embodiment, the arrangement of the driver housings and the manner in which they fit into the protective case is such that there is room to accommodate an inertial sensor integrated circuit (e.g., a digital accelerometer chip) located below the bottom surface of the low driver housing and behind the protective case. An inertial sensor may be used as part of the non-acoustic microphone to detect the voice of the user wearing the headset. Furthermore, an acoustic microphone may be fitted in the protective cover, which may be used as an error microphone in an active noise cancellation system. Another hole may be formed in the protective cover to enable sound from the space between the front face of the protective cover and the rear face of the cover to reach the acoustic inlet of the microphone. The aperture may be positioned such that the inlet of the acoustic microphone is directly behind it, e.g., where the acoustic microphone is located below the bottom side of the second driver housing (or high driver housing) and in front of the front side of the first driver housing (or low driver housing). This makes it possible to use the acoustic microphone not only as an error microphone for an active noise control system, but also as a component of a near-end user or speaker voice pick-up system. The system may be particularly effective when external acoustic background noise is passively reduced by the sealing properties of the flexible ear tip.

The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above and disclosed in the detailed description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically set forth in the summary above.

Drawings

Embodiments of the present invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to "an" or "one" embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. Moreover, a single figure may depict multiple embodiments or aspects of different embodiments of the invention as explained in the detailed description, in order to limit the total number of figures (for reasons of clarity).

Fig. 1 is an exploded view of an earbud with a multi-way driver having first and second driver housings and a crossover circuit according to an embodiment of the invention.

Fig. 2A is a cross-sectional view of an earplug with a three-way driver.

Fig. 2B is a perspective view of the three-way driver assembly shown in fig. 2A.

Fig. 3A is a front perspective view of a protective cover having two ports or channels.

Fig. 3B is a rear perspective view of the protective cover of fig. 3A.

Fig. 4A is a cross-sectional view of an assembly to be installed into an earbud housing, the assembly having a protective cover, an accelerometer, an acoustic microphone, and three driver housings.

Fig. 4B is a bottom view of the assembly of fig. 4A.

Fig. 4C is a rear perspective view of the protective cover used in the embodiment of fig. 4A and 4B, showing another aperture for coupling to the microphone acoustic inlet.

Figure 5 is a perspective view of an assembly of three driver housings, each of which is formed with its sound output port in an outer wall of the housing.

Fig. 6 is an exploded view of several different earplugs, including one having three driver housings and two sound output ports connected to a two-port boot assembly, another having three driver housings and three sound output ports connected to a three-port boot assembly, and a flexible circuit assembly for three-way or two-way earplugs.

Detailed Description

In this section we will explain several preferred embodiments of the invention with reference to the figures. Whenever the shapes, relative positions and other aspects of the components described in the embodiments are not clearly defined, the scope of the present invention is not limited to only the components shown, which are for illustrative purposes only.

Starting with fig. 1, there is an exploded view of a two-way earplug having a first driver housing or shell 2 and a second driver housing or shell 4. At the rear is a headphone housing 1, also called earbud cup, which may be made of a relatively rigid material, such as molded plastic. The headphone housing 1 can be used to accommodate different versions of a multi-way driver assembly, including one having two driver housings 2,4 and another having three driver housings (see fig. 2A). It also serves to enclose the cable wires, which terminate at their proximal end in a jumper circuit 27 inside the housing 1 and at their distal end in an accessory connector (e.g., tip ring sleeve, TRRS, headphone plug-not shown). The cable is used to route the original audio electrical signal from an external device (not shown) to the input of the crossover circuit 27. In one embodiment, the low pass filter and high pass filter outputs of the cross-over circuit 27 are electrically connected by the flex circuit 28 to respective electrical terminals of the first and second driver housings 2,4, respectively. In another embodiment, the crossover circuit 27 or any one or more of its constituent electronic filters may be omitted, for example, when the desired low-pass and/or high-pass behavior can be acoustically achieved by appropriately tuning the driver itself. In both embodiments, the first driver housing 2 may be referred to herein as part of a low frequency driver and the second driver housing 4 may be referred to herein as part of a high frequency driver.

While the driver with the housings 2,4 is able to produce the sound content represented in the original audio signal. The sound content may be, for example, music from digital music or movie files stored locally in an external device or streamed from a remote server and processed and converted to the original audio signal by an audio processor (not shown). Alternatively, the sound content may be the voice of a far-end user of a communication system including an external device during a voice or video call with a near-end user wearing the ear bud. Examples of external devices include smart phones, portable digital media players, tablet computers, and laptop computers.

The earbud cup or housing 1 has an open front end as shown, which receives a multi-way driver assembly, in this case a multi-way driver assembly having at least two different driver housings, a first driver housing 2 and a second driver housing 4. In one embodiment, each driver housing is generally a polyhedron with flat faces and straight sides, but more generally, some of the faces and sides may be curved. There is a manufacturing advantage when the face and sides of the driver housing are flat and straight, respectively. In the particular example shown in fig. 1, each driver housing substantially forms a parallelepiped with a respective main sound output port formed in the wall of each parallelepiped. However, the following description of "faces" and "sides" of the drive enclosure also applies to other polyhedrons. Also, for the sake of clarity, references to "front" and "back", "left" and "right", and "vertical" and "horizontal" are used only to refer to relative orientation and should not be interpreted as having an absolute or limited meaning.

For the first driver housing 2, the sound output port 7 is formed as a tube, which extends outwardly from an outer wall, referred to as the front side 8, as shown. In one embodiment, the sound output port 7 is the main sound output port of the driver housing 2. The rear side of the driver housing 2 is arranged further to the rear of the headphone housing 1 and in the case of the illustrated parallelepiped is substantially parallel to the front side 8. In that case, the left, right, top and bottom sides complete the encapsulation. The sound radiating member or diaphragm 9 is located inside the driver housing 2 and may be oriented substantially parallel, i.e. substantially perpendicular to the sides of the driver housing, as shown, or substantially parallel to the top or bottom surface of the driver housing 2. This is in contrast to the substantially vertical orientation of the diaphragm 3 in the second driver housing 4. Alternatively, the diaphragm 9 may be oriented substantially vertically, i.e. substantially parallel to the sides (rather than the faces) of the driver housing 2. A motor inside the housing 2 (not shown) is attached to vibrate the diaphragm 9 according to the low pass filtered audio signal from the cross-over circuit 27, thereby generating sound.

The second drive housing 4 is also a substantially parallelepiped housing, in this example formed by a front face 6, a rear face, left and right sides, and top and bottom sides. The inner membrane 3 is substantially parallel to the front face 6. The housing 4 is oriented so that its main sound output port is formed in an outer wall of the housing, referred to as the front face 6, while the rear face (opposite the front face 6 in this case) is disposed adjacent the front side 8 of the housing 2. Here, adjacent may mean that there is no intervening space or air gap between the back and front sides, but there may be one or more layers connecting the two, for example, a layer of adhesive material or a layer of vibration dampening material. The rear face of the second driver housing 2 is also positioned behind the outlet of the sound output port 7 of the first housing 2.

The sound output port 5 of the second driver housing 4 is an aperture or opening substantially free of any sound output tube extending therefrom. In the particular embodiment illustrated, although the sound output port 7 of the first housing 2 is a tube that extends substantially forward as shown, forming a short spout as illustrated, there is no such spout for the sound output port 5 of the second housing 4. The sound output port 5 may be substantially flush with the front face 6, which lies flat against the inner face of the boot 10. This helps reduce the depth (front-to-back direction) of the multiplex driver assembly, and may also be designed for a particular nozzle (e.g., with a particular R)_ethe/L ratio) in the relevant frequency range.

The two driver housings 2,4 may be clamped, held or supported by a 2-port boot 10, which may be made of an elastic material, as opposed to the more rigid material used for the earphone housing 1. Examples include silicone or rubber type materials that can stretch and be resilient to grip the exterior of the driver housings 2,4 once fitted into the boot aperture. The 2-port boot 10 has first and

second channels

13, 14 formed in its boot bottom portion as shown, and these channels are aligned with the sound output port of the driver housing when the driver housing 2,4 is fitted into the boot 10. An example of a 2-port boot 10 is shown in fig. 3A, 3B.

The front face or surface of the boot base of the boot 10 is formed with an external ridge 21, which external ridge 21 may completely surround the outlet of the

channels

13,11 as shown, to provide an acoustic seal when pressed against the inner face of the lid 12 (see figure 1). A mixing space 36 may be formed in the front truncated part where the sound from the two

channels

13,11 can mix while being isolated from ambient noise by being surrounded by the outer ridge 21.

Referring to fig. 3B, which shows a perspective rear view of the two-port boot 10 of fig. 3A, it can be seen that an internal ridge 35 is formed on the inner face of the boot 10 that completely surrounds the channel 11. The purpose of the inner ridge 35 is to prevent ambient sound from leaking into the channel 13 and destroying the sound generated by the high frequency driver (housing 2). Note that a similar ridge may not be required for the channel 13, since the sound output port 7 used is an extended tube, which may provide more acoustic isolation (than an opening of the sound output port 5 simply formed as a high frequency driver) due to its contact with the wall of the channel 13.

The boot 10 may be sized so that the cover 12 can fit over the front of the boot 10 so that the resilience of the boot 10 material acts to push against the inside of the cover 12, thereby holding the boot in place. For example, the front face and front side of the boot 10 may be sized to fit snugly into the interior cavity of the cap 12 (entering from the rear of the cap as shown in fig. 1). The cover 12 may be made of a more rigid material than the protective cover 10, e.g. similar to the material used for the earphone housing 1, e.g. in moulded plastic. The cover 12 also serves to complete the relatively rigid earphone housing by, for example, snap-fitting or otherwise snug-fitting to the open end of the earphone housing 1.

The cover 12 has openings in its face which are aligned with the outlets of the first and

second channels

13,11 in the mixing space 36 and the protective cover 10 and which are large enough in area to communicate with the outlets of the first and

second channels

13,11 in the mixing space 36 and the protective cover 10. However, the openings are smaller than the area over which the outer ridges 21 are distributed, so that environmental/background noise is less likely to enter the cover openings. The spout 15 extends forwardly from the front surface of the lid 12 where it is aligned with the lid opening. The mouthpiece 15 may be a generally circular sound tube (e.g., having an oval cross-section) that may or may not taper along its length and provide an uninterrupted space (through the cover opening) in communication with the mixing space 36 and the outlets of the first and

second channels

13, 11. The orifice 15 may be tuned to deliver improved sound quality, e.g., to make its ratio R_eL (equivalent radius R)_eRatio to length L) is in the range 1/4 to 1/7 plus a constant, it being understood that increasing L may achieve a decreasing result.

In the particular embodiment shown in fig. 1, the earplug is a sealed type earplug, wherein an ear tip or earcap 14 attached to a cap 12 is provided to acoustically seal against the ear canal of a user. The ear tip 14 may be made of a flexible foam-type material or other suitable material that is capable of conforming to the shape of the user's ear canal wall, thereby providing an acoustic seal, e.g., an acoustic seal that completely surrounds a channel (shown in phantom) formed in the ear tip 14. Which is designed to receive the forward portion of the spout 15 therein. Suitable mechanisms are also provided to keep the ear tip 14 attached to the cap 12 including the spout 15 as the user repeatedly inserts and removes the earbud from his ear.

In the embodiment of fig. 1, the second driver housing 4 may be a housing of a balanced armature driver, with a sound output port 5 (opening, such as a slot or circular hole) formed in a front face 6 that is part of the outer wall of the driver housing 4. In one embodiment, the housing wall completely encloses the chamber in which the membrane 3 is positioned so as to be substantially parallel to the front face 6 as shown. The diaphragm 3 is the main sound producing or radiating member and will vibrate according to the audio signal converted by the motor. The audio signal driving the balanced armature motor may be a high pass filtered version of the original audio signal delivered by the electrical cable 26 to the earplugs-see fig. 1. The cross-over circuit 27 may high-pass filter the original audio signal at one of its outputs and may also low-pass filter the original audio signal at the other of its outputs to achieve the two-way earplug operation shown in fig. 1. The low pass filtered version is sent to the input electrical terminals of the first driver housing 2. Note that in a three-way earbud (such as the earbud shown in fig. 2A), the crossover circuit 27 may also be bandpass filtered at another output, with the bandpass filtered version being sent to the input electrical terminal of the third driver housing (the midrange housing 18 in fig. 2A). Alternatively, the crossover circuit 27 may be omitted for a particular driver so that the original audio signal in this case may be routed to the driver input terminals in the driver housing.

Turning now to fig. 2A, a cross-sectional view of a three-way earbud is shown having a three-way driver in which a woofer housing is provided that is larger than a midrange housing, which in turn is larger than a tweeter housing. In this case, the earpiece housing 1 and the cover 12 may be substantially similar to those of the two-way earpiece shown in fig. 1. In addition, the ear tip 14 may be similar. As another similarity, the two-port boot 10 can also be reused for a three-way driver, where the upper channel 13 is shared by both the low frequency driver (i.e., the woofer 16) and the mid frequency driver 18. This may be accomplished by providing an acoustic output port in the top surface of the housing of the woofer 16 that is aligned with an input port formed in the bottom surface of the housing of the midrange 18 as shown. The thickest arrows in fig. 2A represent low-frequency or bass sounds produced by the woofer 16, while medium-thickness arrows represent mid-frequency sounds produced by the mid-frequency driver 18, and thin arrows represent high-frequency sounds produced by the tweeter 17. As shown, high frequency sound from the tweeter 17 is imparted to its own dedicated channel 11 in the two-port protective cover 10.

The low frequency driver housing, i.e., the housing of the woofer 16, has a rear side in which the driver input electrical terminals 33 are exposed and connected to the flexible circuit 28, a front side, a top surface, and a bottom surface. The low frequency driver housing is stacked flat below the housing of the mid frequency driver 18, where the latter also has a rear side in which the driver input electrical terminals 32 are exposed and connected to the flex circuit 28, a front side, a top surface and a bottom surface. Furthermore, the housing of the midrange speaker 18 has a sound output port 7 which extends from the front side (see also fig. 2B) as an acoustic tube through which both low and midrange sounds are delivered into the mixing space 36 of the protective cover 10-see fig. 3A. Stacking the midrange 18 and woofer 16 may also be described as positioning the bottom face of the housing of the midrange 18 adjacent the top face of the housing of the woofer 16.

To complete the three-way driver assembly, the housing of the tweeter 17 is oriented such that its sound output port 5 is formed only as an opening in the front face 6 of the housing, while the rear face of the housing is adjacent the front side 19 of the housing of the woofer 16. In addition, the rear of the tweeter housing is positioned behind the outlet of the sound output tube of the housing of the midrange 18. In this configuration, the outlet of the mid-range sound output tube is substantially aligned with the front face of the tweeter housing so as to reduce the depth of the three-way driver assembly. This arrangement is also shown in fig. 2B, where in this case the sound output port 7 emerges from the front side 8 of the housing of the midrange speaker 18, while the sound output port 5 is formed in the front side 6 of the housing of the tweeter 17.

Note that in the embodiment of fig. 2A and 2B, each of the driver housings is substantially a parallelepiped. For example, the top surface of a woofer housing, like the bottom surface, has a larger area than either the rear or front side of its housing. Further, each of the top and bottom surfaces of the midrange speaker housing can have a larger area than any of the side surfaces. Each of the front and rear faces of the enclosure of the tweeter 17 has a larger area than the left and right sides, but not necessarily larger than the top and bottom sides. With such an arrangement, in one embodiment, the diaphragm 3 of the tweeter 17 is oriented substantially vertically, or substantially parallel to the front and rear of the tweeter housing, as shown, while the diaphragms 9b,9a of the midrange 18 and woofer 16, respectively, are substantially horizontal, or parallel to the top and bottom surfaces of those housings. Referring to fig. 4A, a cross-sectional view of the three-way driver assembly is shown, and in particular, the diaphragm 3 in the tweeter 17, the diaphragm 9a in the woofer 16, and the diaphragm 9b in the midrange 18.

Fig. 2A and 2B also show how the flexible circuit 28 is connected to its cross-over circuit 27, in which case the cross-over circuit 27 has three outputs, providing a low pass filtered version, a band pass filtered version and a high pass filtered version of the original audio signal delivered to the earpieces through the cable 26. As can also be seen in fig. 2B, in this embodiment the flex circuit 28 has two sections, one section extending substantially vertically and connecting the electrical terminal 33 of the woofer 16 to the low pass filter output and the electrical terminal 32 of the midrange 18 to the band pass filter output, and the other section routing back from the electrical terminal 34 of the tweeter 17 and connecting to the high pass filter output by extending along the top surface of the woofer housing as shown. Note also how a section of the flex circuit 28 extends along the top surface of the woofer housing and along the left side of the midrange housing, while the right side of the midrange is positioned closer to the right side of the woofer housing, as shown in fig. 2B. This arrangement also helps to reduce the volume of space required inside the earplug housing 1.

In one embodiment, still referring to the three-way earbud of fig. 2A and the three-way driver assembly of fig. 2B, the tweeter 17 may have a balanced armature motor inside its housing that is coupled to drive the diaphragm 3. For the motors used in woofer 16 and midrange 18, these motors may or may not be of the balanced armature type, as one or both of them may instead be a change in electrodynamics.

Referring now to fig. 4A, a cross-sectional view of a three-way driver assembly in combination with an acoustic microphone 38 is shown. The latter may be used as part of a digital acoustic pickup circuit (not shown) which may include an analog to digital conversion circuit connected to the flex circuit 27 and may be located near the crossover circuit 27. The microphone 38 may be fitted into a so-called "digital" boot 39. The latter may be substantially similar to the 2-port boot 10 described above, except that as shown in fig. 4B and 4C, additional openings or holes are created to enable sound from the mixing space 36 between the front of the boot 39 and the rear of the lid 12 to reach the acoustic inlet of the microphone 38. In the example shown here, the microphone 38 is located below the bottom side of the housing of the tweeter 17 and in front of the front side of the housing of the woofer 16. This arrangement is particularly space efficient because the lower section of the flexible circuit 28 can be electrically connected to the microphone 38, extending from the electrical output terminals of the microphone 38 back along the bottom surface of the woofer housing and then up to connect with the terminals of the woofer 16 and then forward to connect with the terminals of the midrange 18. The digitized audio signals picked up by the microphone 38 represent sound in the mixing space 36, which is essentially sound generated in the ear cavity of the user wearing the ear plug. Such digitized audio signals may be delivered to an active noise control or cancellation (ANC) processor, which may be implemented in an external device (which simultaneously produces the original audio signals that are sent to 3-way drivers for conversion to sound), through a cable 26, see fig. 2A. In that case, microphone 38 may be referred to as an error microphone that is used by the ANC processor to pick up residual acoustic noise that may be heard by the user during the ANC processing operation.

Referring to fig. 4B and 4C, the opening for sound to reach the microphone 38 has a through hole section, i.e., a hole that passes through the wall of the boot 39, and a groove section, i.e., a groove formed in the outer surface of the wall of the boot wall, that connects the through hole section to a region in front of the front face of the boot (boot) 39 inside the periphery of the outer ridge 21. This is best seen in the bottom view of the protective cover 39 shown in fig. 4B. To achieve such a groove segment, as shown in fig. 4B, a corresponding portion of the outer ridge 21 has been removed (or not formed). This in turn allows sound from the mixing space 36 to spread across the front of a boot (boot) 39 and then pass along the groove section and then along the through hole section before reaching the acoustic inlet of the microphone 38, to the location of the acoustic microphone 38.

Returning to fig. 4A and 4B, these figures also show another embodiment of the invention in which an inertial sensor 37 (e.g., a digital accelerometer chip) may be attached to the outside of the flex circuit 27 (while the microphone 28 is attached to its inside), while being located below the bottom surface of the low frequency speaker 16 and behind the protective cover 39. In this way, the bottom of the inertial sensor 37 may be in direct contact with the inner surface of the outer wall of the earpiece housing 1 in order to better pick up vibrations of the outer wall of the earpiece housing 1 caused by bone conduction when the earpiece wearer speaks. To improve performance, vibration dampening or absorbing material may be added between the inertial sensor 37 and the bottom surface of the woofer 16 to dampen pickup of low frequency vibrations generated when the woofer 16 converts the original audio signal. The digitized inertial signals (from inertial sensors 37) are routed here using flex circuit 27 to cable 26 (see fig. 2A), which cable 26 in turn routes the signals to an external audio device. Within the external device, the inertial signal may be processed by a combined acoustic and non-acoustic voice activity detection processor to determine whether the user (wearing the earbud) is speaking.

Figure 5 is a perspective view of an assembly of three driver housings, each of which has a respective sound output port formed in an outer wall thereof. This embodiment is similar to the 3-way driver assembly shown in fig. 2B, except that the housing of the woofer 16 has a sound output port 20 (in this case a tube) extending outwardly and upwardly from the outer wall of the right side of the housing. The outlet of this bass output tube (sound output port 20) fits into a channel 25 formed in the boot bottom of the 3-port boot 22. The latter has two

additional channels

24, 23 which are aligned with the outlets of the midrange speaker sound output port 7 and the tweeter sound output port 5, respectively, as shown. For a 3-port boot 22, the mixing space 36 (see fig. 3A for a 2-port boot 10) is open to the outlet ports of all three

channels

23, 24, 25, so that the respective sounds are first mixed together outside the boot 29 in the space between the front of the boot 29 and the rear of the lid 12. This arrangement is similar to the earplug with the 2-port boot 10 shown in fig. 1, where it is understood that for the 2-port boot 22, the cap opening from which the spout 15 extends forwardly will communicate with the mixing space 36 while remaining within the perimeter of the outer ridge 21.

Fig. 6 is an exploded view of several different earplugs as described above, all of which may share the same housing 1, cover 12 and earmuff 14, but using different combinations of boots and multi-way driver assemblies. In one case, the 2-port boot 10 is used in combination with a 2-way driver assembly (see fig. 1) or a 3-way driver assembly (see fig. 2B). In another embodiment, a 3-port boot 22 is used in combination with a 3-way driver assembly having separate sound output ports for all three drivers that extend from their respective housing walls and then communicate directly with their respective channels in the boot 22-see fig. 5). In another embodiment, a digital boot 39 is used which allows for mounting of the acoustic microphone 38 on the flex circuit 28, wherein it should be clear that either a 2-way or 3-way driver assembly may be used in such embodiments.

While certain embodiments have been described, and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art. For example, although the driver housings depicted in the figures are polyhedrons, the "sides" of the driver housings may alternatively be a single continuous smooth wall (like a ring) that wraps around, rather than discrete faces in a polyhedron. Also, while fig. 1 and 2A show an earplug of the sealed type, wherein a flexible ear cap or tip 14 is fitted to the cap 12, one alternative is to omit the tip 14 and shape the cap 12 and spout 14 to achieve a loosely fitted, non-sealed earplug. The description is thus to be regarded as illustrative instead of limiting.

Claims

1. An earbud driver assembly, comprising:

a low drive housing having a rear side, a front side, a top side, and a bottom side;

a mid driver housing having a rear side, a front side, a top side and a bottom side, a sound output opening in the front side of the mid driver housing, wherein the bottom side of the mid driver housing is joined to the top side of the low driver housing; and

a high driver housing having a top side, a bottom side, a front face and a rear face, a sound output opening formed in the front face of the high driver housing, and wherein the rear face of the high driver housing is joined to a front side of the low driver housing.

2. The earbud driver assembly of claim 1, wherein each of the top face of the low driver housing and the bottom face of the low driver housing has a larger area than either the back side or the front side of the low driver housing.

3. The earbud driver assembly of claim 1 further comprising a driver electrical terminal exposed on the rear side of the low driver housing and another driver electrical terminal exposed on the rear side of the mid driver housing.

4. The earbud driver assembly of claim 3 further comprising:

driver electrical terminals exposed on the left or right side of the high driver housing; and

a flexible circuit that routes wire back from the driver electrical terminals of the high driver housing by extending along a top surface of the low driver housing.

5. The earbud driver assembly of claim 1 further comprising a balanced armature motor located inside the high driver housing, the balanced armature motor being coupled to drive a diaphragm oriented parallel to the front face of the high driver housing.

6. The earbud driver assembly of claim 1 further comprising a sound output tube extending outward and then upward from a left or right side of the low driver housing.

7. The earbud driver assembly of claim 1 further comprising a boot having a first channel and a second channel formed therein, wherein the low, medium, and high driver housings fit into the boot with the first channel aligned with the sound output opening of the medium driver housing and the second channel aligned with the sound output opening of the high driver housing.

8. The earbud driver assembly of claim 7 further comprising a sound output tube extending outward and then upward from a left or right side of the low driver housing,

wherein a third channel is formed in the boot, the third channel being aligned with an outlet of a sound output tube extending from the low driver housing.

9. The earbud driver assembly of claim 7 further comprising a cap having an opening that is aligned with and large enough to surround the outlets of the first and second channels in the boot.

10. The earbud driver assembly of claim 9 further comprising an ear tip that fits onto the cap.

11. The earbud driver assembly of claim 10 further comprising a microphone that fits into the boot, another hole formed in the boot that enables sound from a space between a front face of the boot and a rear face of the cap to reach an acoustic inlet of the microphone.

12. The earbud driver assembly of claim 11, wherein the microphone is located a) below a bottom side of the high driver housing and b) in front of a front side of the low driver housing.

13. The earbud driver assembly of claim 11 further comprising an earbud housing in which the boot, the low driver housing, the mid driver housing, and the high driver housing are mounted, and an inertial sensor located in the earbud housing.

14. The earbud driver assembly of claim 13 further comprising a flex circuit electrically connected with the microphone, the inertial sensor, and the low and mid driver housings, wherein the flex circuit extends from the microphone back along a bottom surface of the low and mid driver housings and then up to connect with the low and mid driver housings.

15. The earbud driver assembly of claim 9 further comprising a spout extending forward from the cap, wherein the spout is aligned with the opening of the cap, wherein the spout provides an uninterrupted space in communication with the outlets of the first and second channels at the opening of the cap, wherein the spout is fitted with an ear tip thereon, and wherein the spout has an equivalent radius to length ratio in a range from the sum of 1/4 and a constant to the sum of 1/7 and a constant.

16. An earbud driver assembly, comprising:

a low-frequency driver is arranged in a parallelepiped shell,

a mid-frequency driver parallelepiped housing stacked on and bonded to the low-frequency driver parallelepiped housing;

a high frequency driver parallelepiped housing, a rear face of which is joined to a front side of the low frequency driver parallelepiped housing, and a sound output port of which is an opening in the front face of the high frequency driver parallelepiped housing.

17. The earbud driver assembly of claim 16 further comprising a balanced armature motor inside the high frequency driver parallelepiped housing coupled to vibrate a diaphragm, wherein the diaphragm is positioned parallel to a front face of the high frequency driver parallelepiped housing.

18. The earbud driver assembly of claim 16 further comprising:

a cross-over circuit; and

a flex circuit electrically connected to the jumper circuit, and wherein the flex circuit runs wire from the driver input terminals in the high frequency driver parallelepiped housing back and along the top face of the low frequency driver parallelepiped housing adjacent to the left or right side of the mid frequency driver parallelepiped housing.

19. The earbud driver assembly of claim 16 further comprising:

an elastic protective cover gripping the low frequency driver parallelepiped housing, the intermediate frequency driver parallelepiped housing and the high frequency driver parallelepiped housing.